Repeater apparatus



Sept. 22, 1931. w. H. EDWARDS REPEATER APPARATUS Filed May 14. 1929 7\ Output INVENTOR BY WEE/Myard? f ATTORNEY Patented Sept. 22, 19.31

UNITED STATES PATENT o1-FICE WILLIAM H. EDWARDS, 0F GREAT NECK, NW YORK, ASSIGNOR T0 AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, CORPORATION OF NEW YORK REPEATER AHARATUS Application med Kay 14,

Thisk invention relates to a method of and means for varying the impedance of an element and more particularly to the utiliza- ,tion of such principles and apparatus for the 5 transmission and repetition of sound energy. In the operation of the arrangements of the invention, a device such as a thin film rectifier, for example, a disk of copper and cuprous-oxide, is included 1n a c1rcu1t and lo subjected to external stress. It has been found that subjecting a device of this character to stress will vary its impedance 1n the circuit. In accordance with the arrangements of this invention, the stress to which the device is subjected is caused by utllizing the device as an armature for an electromagnet in another circuit over which voice waves are being transmitted. Underv such conditions, the device ma operate as a telephone repeater. Other o jects and features of the invention will appear more fully from the detailed description thereof heremafter given.

For purposes of illustratlon, 1t will be assumed that theelement whose lmpedance 1s vto be varied by the method of this invention, may be a rectifier of the well known copper oxide type. However, other types of t 1n film or contact rectifiers may be utilized.

` 3 One of the suitable methods of forming the rectifier element might consistin heating a copper sheet about .005 thick to over 1000 C. until a thin closely adherent layer of cuprous oxide about one or two thousandths of an inch is formed. A heat treatment is then administered at lower temperatures. The outer surface of the oxide may then be reduced to metallic copper by electrolysis. The impedance element 1n the circuit might be formed of one or more of such units.

At the junction of the bulk of the cuprous oxide and the mother copper there is believed to be a transition layer, wherein the copper oxide crystals match perfectly the copper crystals which they adjoin. This transition layer is of high resistivity but in formation is made to match on to the copper in such a way (probably with considerable stress in the transition layer) as to reduce to a low value, the work function of escape into it of elec- 1929. Serial No. 368,085.

trons from the copper. However, it matches on to the adjoining cuprous oxide in such a Way as to make a largework function. There is no such effect between the thin metallic copper on the outer surface of the oxide as` between the mother copper and the oxide due to the different manner in which it is formed. Based on the theoryiof a transition layer depending upon initial stresses, or on substantially perfectly matched crystals, it is proposed in accordance with the principles of this invention to vary the stresses in this transition layer or the manner in which the crystals are matched and thus vary the'work functions. Inasmuch as the oxide and surface coating of copper are very thin, the transition layer is near the surface of the rectifier plate and is subject to approximately the maximum fibre stresses existing in the plate when it is fixed. Furthermore, when a portion of the plate bends in one direction, the transition layer has tension stresses superimposed on the initial stresses, and

Vwhen bent the other way, has compression stresses added to it. It has been found by experiment that bending a plate so that the oxide is. placed in tension instantly increases the resistance in the Vreverse direction and that when placed in compression, the opposite occurs. It has also been found that variations in ressure cause variations in resistance in t e conducting direction. Also, if kept within proper limits, it appears that this fiexure can be continued indefinitely without deterioration of the disks.

The characteristics of the thin film rectifier disk would adapt it for use as a telephone repeater in accordance with the arrangements of this invention. The weak alternating currents coming ,in over the line would be utilized to energize the coils of an electromagnet to cause it to attract or repel an armature attached to the rectifier disk. This would vary the stress to which the device was subject and varv its impedance in the secondary circuit in which it was connected. In this secondary circuit, there would be a source of energy. This action would cause a modulation of the comparatively large amount of direct current flowing in the secondary ciri stood from the following detailed descrip-v cuit in accordance with the incoming currents. By separating the alternating current component therefrom by use of a transformer, the amplified output current is available. Y

The invention may he more fully undertion together with the accompanying drawings in the Figures 1, 2 and 3 of which the invention is illustrated. Fig. 1 is Ya circuitv diagram illustrating an embodiment. of theV invention. Fig. 2 isa sectional showing of the repeater element of the invention.. In.'

Fig. 3 is shown a curve illustrating the resistance-voltage characteristics of the 'recti-4 fier disk utilized in the invention.` 4

In Fig. 1 is vshown a. portion of a circuit 1 over which sound waves are being transmitted. j Included in this circuit is the winding of an electromagnet 2. Adjacent to the f pole piece of magnet 2, is an armature 3v of magnetic material mounted on the ,stressed Vthin film rectifier disk 4f, which may be of copper and copper oxide.v This disk would be connected in a circuit with the battery 5 and the winding of transformer 6.l AnA out-` put circuit would in turn be connected to transformer 6. The weak alternating currents coming in over line 1 will energize magnot 2 and cause it to attract or repel the ar-V repeater apparatus. Similar reference char-V acters have been utilized to denote like parts -with respect to Fig'. 1. The leads 20-and 21V would be connected to .the sides of circuit 1- and would be connected to the windings 18 and 19 of the electromagnet 2. Adjacent to' the pole pieces of magnet 2 is the armature 3 of magnetic material whichY may be repelled vor attracted by the energization of coils 18 and 19. The armature 3. is affixed to the 'stressed thin film rectifier disk 1l. This disk has had its thickness shown as exaggerated for purposes of illustration, and-may becomposed of a copper section 10, an'oxide film 11, and a surface iiash of copper l2. It is pointed out that other metals than copper `might be utilized in the make-up of the disk.

Y The'disk may be held in position byl an insulated clamping member 7 and a casing 8. vThe casing 8 may bein Contact with one side of the disk and 'will be connectedto terminal `15. A contact ring 13 will be provided in con- 1,s23,933 i L. Y

tact with the other side of the disk. To this may be connected-the terminal 14C. Terminals lll and 15 will be connected to the secondary circuit including'tlie battery 5 and the winding of transformer 6.

ln Fig. 3 there is shown a curve illustrating the resistance-voltage characteristics of certain types of thin film rectiiiers, such as those of the copper oxide type. lt is pointed out .that the most efficient portion ofV thecurve .on which to operatethe device-as a repeateramplifier in accordance with the arrangements v.ofthe invention, is between the point of zero voltage, where the resistance is comparatively high, and theknee of the curve in the conducting direction,.ivhe`re the resistance is comparatively low. Operation on the downward Vslope of the curve in the reverse direction would also have a somewhat similar effect. A y

l/Vhile the invention has been disclosed as embodied in certain specific arrangements which yare deemed desirable, it is'understood that it is capable of embodiment in,V many other and widely varied forms without de'- parting lfrom the spirit of the invention as defined in the appended claims.

lVhat is claimed is:

Y 1.111 a transmission system comprising a circuit including a source of vcurrent and a disk having a stressed transition layer between two substances, the method of repeating sound energy which comprises causing sound waves coming in over an adjacent circuitv tovary the impedance in its circuit of 'said transition layer byV superimposing stresses on. the layerfbyiiexing said fdisk.

2. In atransmission system comprising a circuit including a source ofcurrent and a disk having a stressedV transition layerl between two substances, the method of repeat- Y' ing sound energy which comprises vcausing sound waves. coming in over an adJacent circuit to vary y,the impedance in its circuit of said transition layer by superimposing stressi es on the .layer by flexing said disk and therebyfvarying its impedance in its circuit pro.-l

portionallyto. said incoming sound waves and selecting the alternating current component fromthe current in said iirst mentioned circuit. .s Y

8.1i transmission system comprising an incoming line section, a magnet included therein, an intermediate line sectionincluding a source of energy.. and aV thin vfilm rectifier disk, said disk including a stressed transition layerV between two substances and being so positionedas'to bend under :the magnetic control of saidinagnet thereby varying the stresses and impedance on 'the transition layer, and an output circuitinductively connected to said intermediate circuit.

4. In av transmission syst-emV comprising a source of current and a disk having a stressed transition layer between two substances, the

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